Ultrasonic diagnostic apparatuses are used for medical diagnosis. These apparatuses monitor living bodies in vivo for diagnosis, using ultrasonic echo images formed by reflection in the living body. In addition, photoacoustic apparatuses using light have recently been developed for diagnosis. Photoacoustic apparatuses are intended for medical diagnosis. Such an apparatus irradiates a test area of a living body with light so that the measuring target is thermally expanded to generate acoustic waves (typically ultrasonic waves), and displays an image according to the signal of the acoustic waves. Such an acoustic diagnostic apparatus can measure specific substances at the test area, such as glucose and hemoglobin in the blood.
The quality control of such diagnostic apparatuses used for medical purposes is necessary for accurate diagnosis. Phantoms are used as reference materials for quality control and calibration of the diagnostic apparatuses.
Phantoms are required to propagate ultrasonic waves generated from a target that is a mimic tumor therein (or waves reflected from the target or the interface). In order to ensure highly accurate quality control and calibration of diagnostic apparatuses, the entirety of a phantom must have acoustic properties similar to the living body.
As phantoms used for quality control, urethane gels are generally used. Urethane gels are stable in physical properties with time and have acoustic properties close t to those of the living body. For example, PTL 1 discloses a urethane gel having optical and acoustic properties controlled for use as photoacoustic phantoms, produced by curing a copolymer of ethylene oxide and propylene oxide with an isocyanate. PTL 2 teaches that a urethane gel produced from polybutadiene polyol and diphenylmethane diisocyanate has acoustic properties suitable for use as ultrasonic phantoms.